1. Field of the Invention
The invention relates to the field of aquatic recreation apparatus and in particular concerns a flotation tube that is nestably coupleable to other similar tubes to form a semi-rigid elongated train. Laterally spaced flexible straps hold successive tubes together at complementary convex/concave abutting surfaces that allow the train to bend around a curve but the structure is such that the train cannot collapse or buckle, for example, when the front tube(s) encounter an obstruction such as a splash down pool.
2. Prior Art
A waterslide typically involves a path with an elongated trough or sluice in which water flows, in an amount at least sufficient to wet the surfaces and in many instances moving a substantial volume of water per unit time. The trough usually defines a continuously downward flow path and drains water that is pumped upwardly from a splash down pool at the end of the course to an entry point at the entrance.
There are various known configurations. A deep water ride may carry a flow on which riders float, or the riders may skim over a thin layer of water, or a gush of water may carry the riders along turbulently. A course may be relatively steep or have a mild gradient. In an uphill/downhill course the water may pool in the valleys and require draining or the course may have some places where the water is relatively deep and/or fast flowing and other places that are merely wetted, such as uphill runs. For excitement, the course often has banked turns.
The nature of the flow of water is determined by the contour of the sluice, including its width, curvature and vertical gradient, and by the amount of water flowing in the sluice at any particular point. Sluices or slides can lead to intermediate pools, and outlets or alternative outlets from intermediate pools can lead to further slides, etc.
The sluice can define a sinuous path, and the curves are correspondingly banked such that the flow of water due to inertia is not restricted to the lowest cross-sectional portion of the sluice, but rather rises along the sides of the sluice. Accordingly, in traversing turns the riders become canted to an angle defined by the surface of the water flowing around the turn.
Waterslide riders can traverse the slides with or without flotation devices or sliding mats, however such devices are preferred due to their ability to protect the rider from friction with the sluice. Flotation devices also support the riders in relatively deep water. Whether a particular waterslide sluice is apt for persons alone or for persons with flotation devices is a matter of the width of the sluice, the character of its surfaces, the rider's speed and the flow of water. The sluice width is such that the rider or the rider's flotation apparatus is confined between the sidewalls. The sluice may be correspondingly narrow to prevent the rider or flotation device from turning laterally to the flow and obstructing flow and traffic or subjecting the rider to friction along the sluice sidewalls.
Air mattresses have been used for flotation in waterslide parks, as have vehicle inner tubes. However, an air mattress or inner tube of the type often used for placid floating may not be suitable for riding a waterslide. Accordingly, reinforced and adapted versions of such flotation devices have been developed. For example, U.S. Pat. No. 5,020,465--Langford discloses a variation on an inner tube, having a relatively sharper prow and blunt stern with complementary couplings permitting the attachment of several such devices in lines or arrays. U.S. Pat. Nos. 5,011,134 and 5,230,662 disclose sliding mat variations having toboggan-like fronts and handles. U.S. Pat. No. 5,453,054--Langford discloses a different tube variation with couplings that, like Langford '465 are pivotable on a vertical axis. The foregoing patents disclose various details of flotation devices as well as waterslides, and their disclosures are hereby incorporated.
Tubes are comfortable and convenient flotation devices because a person can sit comfortably upright in the central opening defined by the tube, with the user's legs hanging over the sides. Durable versions of the tubes having fabric surfaces resist damage from friction, for example the friction occurring between the tube and the sides of waterslide sluices. Such tubes are typically made of resin embedded in a fiber as the wear-resistant external skin of an inflatable tube. The tubes can have handles on the top surface, to steady a rider when sitting upright, and back rests, etc. Due to these beneficial attributes, tubes have become a preferred form of flotation device for waterslide parks wherein the riders traverse a sluice on an individual flotation device.
Single and multiple tubes and tube connections are possible. Riders of waterslides frequently attend in or form groups. Members of a group find it enjoyable to traverse the slide together. Although traversing the sluice one after another is in a sense traversing the sluice together, riders may join hands and traverse the slide single file. Of course, when joining hands makes it difficult to maintain a hold on any handles that may be provided on the rider's tube. To serve the users' desires, park operators may supply an integrally double tube or "double doughnut" wherein an inflatable body in a figure eight shape provides apertures for two riders to sit. Such a device is relatively rigid and is impractical in units of more than two rider positions. The long longitudinal axis causes wear on the tube when traversing curves or limits the minimum radius of curves, or cause wear at vertical diversions and changes in slope, or causes problems in wider areas such as pools.
US Pat. No. 5,507,674--Yeung discloses a plurality of tubes that are coupleable in a single file by pairs of mating connectors on opposite sides of the tubes. The connectors in the pairs are spaced on the tube and the round shape of the tube causes the tube to protrude between the connectors. Thus, connected tubes bear relatively tightly against one another between the connectors, providing a train of tubes that is substantially as rigid as a double doughnut type. The Yeung patent is also hereby incorporated.
The coupled single rider tubes of the Langford '465 and '054 patents, which pivot on a vertical coupling axis, ameliorate the difficulty with rigidity and permit a line of two or more connected tubes to bend to follow a curve. However, other problems are presented. The couplings permit a certain longitudinal play or slack in the train. The couplings also are quite free to pivot, both on a vertical axis and a horizontal axis. As a result, when a line of coupled tubes encounters an obstruction, the train of tubes can be longitudinally compressed and may tend to collapse into an accordion fold. This can occur at points such as a splash down pool when the leading tube(s) of a fast moving tube train encounter the obstruction of deep water, and is undesirable.
To deal with accordion fold collapse, a designer may choose to reduce the gradient of the course so that obstructions such as the splash down pool do not produce the sudden braking that causes such collapse. However, this reduces the speed and excitement of the ride. Alternatively the designer may choose an integral multi-rider tube or another rigid train arrangement. However, all the curves along the course then are required to have a minimum turning radius that will accommodate the longest rigid tube train, which also reduces the excitement of the ride. What is needed is a tube train structure that balances the need for flexibility, for negotiating turns and gradient changes, with the need for structural integrity and rigidity of the train of coupled tubes.